1. Field of the Invention
The present invention relates to an aqueous dispersion adhesive composition and an adhesive film.
2. Description of Related Art
Heretofore, optical films such as polarizing film, phase difference film, luminance improving film and view-angle expansion film have been used in various industrial applications and, for example, these optical films are used for sticking onto image display devices such as liquid crystal display, organic electroluminescence device (organic EL display device) and plasma display panel (PDP).
As the optical film, an adhesive optical film including an optical film laminated with an adhesive is known.
In recent years, from the viewpoint of environmental burden, it is desirable to reduce the use of organic solvents, and shifting from solvent adhesives using an organic solvent as a solvent to aqueous dispersion adhesive using water as a dispersion medium is desired.
As such the aqueous dispersion adhesive, for example, there has been proposed a pressure-sensitive adhesive composition having an emulsion of a copolymer in which 2-ethylhexyl methacrylate is copolymerized in an amount of 10 to 50% by weight of the whole copolymer, the copolymer having a glass transition temperature of −25° C. or less (cf. for example, Japanese Unexamined Patent Publication No. 2001-254063).